Coolant Leak

Never leave the cap loose. You are keeping the recovery tank from depleting but the cooling system is losing fluids through the cap and you are not going to notice it until it is too late.

The cooling system works under pressure and the main purpose of the cap is to keep the pressure constant.

Depleting in 2 days means the leak is not too big to drip but should be sufficient to show with a pressure test. I don't understand why the leak cannot be detected. Was the heater core checked ?

Try a dye test.

If pressure test is done with warm engine and did not show anything, do it when engine is cold. Keep attention on hose joints.

Hoses have been replaced twice. Not sure if heater core has been checked. Will try that. Picture is location of drip after filling coolant, driving 15 miles & after parked for a few hours. Drove home & parked car overnight. Spill was twice as large the next morning.

If you leave the rtadiator cap loose, that is what to expect. Coolant would be spilled out of the radiator neck.

Coolant leaves behind streaks of oxidation when they dry up. Visual inspection should show you something.

Keod - did you ever find the source of your leak? I have the *exact* same leak on my Tribute and I'm wondering what it is.

Leaks can be from any part of the cooling system and a pressure test would be necessary to find the leaking point. If leaks are low, chemical test would be the best way to go about.

I did! Amazingly enough, although each mechanic had done pressure tests, none has done a dye test. So my sister and got into girls rule mode and removed the hose at the coolant container (there's no radiator cap in a Mazda) poured in the dye and looked the next morning. She had a black light (which flabbergasted me) but the dye shows up very well without it. It was a hose. A hose that had been replaced twice. Long story short, it was bubbling on the pipe the hose was on so with the expansion & contraction, the coolant leaked out from those small gaps. One of the mechanics who tried to find the leak & who happens to specialize in exhaust repair,, smoothed out the pipe (Mazda of course doesn't sell the replacement part anymore), reattached the hose, and I've been leak free ever since. So but the dye, it cost a little over $2 and the best part was the mechanic didn't charge me a cent. Good luck!

Thanks for the update. Nice work.